The transition section (TS), linking the front bend and the back bend in consecutive river bends, plays a key role in the flow hydraulic characteristics, sediment transport, and riverbed evolution in meandering rivers, which is crucial for flood control, navigation, and river stability. Most existing studies on the hydraulic effect of the TS focus on flat-bed scenarios, rendering an inadequate understanding of the TS in consecutive bends with point bars, often found in natural rivers. Based on three-dimensional numerical simulations, the effects of the length and the topography of the TS are investigated in detail on the flow structure in consecutive bends with point bars, respectively. The results reveal that without an adequate TS length, the residual circulation of the front bend (RC) inhibits the development of the main circulation in the back bend (MC), causing the positions of the maximum strength of the MC and the maximum value of cross-section-averaged turbulent kinetic energy ($<\widetilde{tke}>$) in the back bend moving upstream. As the length of the TS increases, the above effect of the front bend gradually decreases. The critical length of the TS to fully decay the RC is 4.8 times the bend width (B) in consecutive bends with point bars, longer than that (4B) in the flat-bed bend. Furthermore, the central bar in the TS is found to facilitate the generation of the outer bank cell and accelerate the decay of the RC. These effects of the TS can profoundly change the flow hydraulics, sedimentation, and stream stability of consecutive bends. The results of the study will help to further understand the linkage role of the TS in consecutive bends and may serve as a rational reference for managing natural meandering rivers with multiple hydrological, geomorphological, and/or ecological goals.

过渡段（TS）连接连续河道中的前弯和后弯，对曲流河流的水力特征、泥沙输移和河床演化起着关键作用，对防洪、通航、防洪、防洪、航运等方面具有重要作用。河流稳定。现有的大多数关于 TS 水力效应的研究都集中在平板场景上，对天然河流中常见的带有点坝的连续弯道中的 TS 的理解不够充分。基于三维数值模拟，分别详细研究了 TS 的长度和地形对点筋连续弯道中流动结构的影响。结果表明，如果没有足够的TS长度，前弯（RC）的残余循环会抑制后弯（MC）主循环的发展，导致MC的最大强度和最大值的位置截面平均湍流动能 ($<\stackrel{～}{tke}>$）在后弯向上游移动。随着TS长度的增加，前弯的上述效果逐渐减弱。完全衰减 RC 的 TS 的临界长度是点钢筋连续弯曲中弯曲宽度 ( B ) 的 4.8 倍，比平板弯曲中的 (4B)长。此外，发现 TS 中的中心条有利于外层细胞的生成并加速 RC 的衰减。 TS 的这些影响可以深刻地改变连续弯道的流动水力、沉降和水流稳定性。研究结果将有助于进一步了解TS在连续弯道中的联动作用，并可为管理具有多种水文、地貌和/或生态目标的自然曲流河流提供合理参考。